Introduction 1 2 3 4 5 6 7 Methods The study was conducted in the St. Antonius Hospital, a 600-bed teaching hospital in Nieuwegein, The Netherlands. Patient population This was a prospective observational study of patients with confirmed pneumonia admitted between October 1, 2004 and August 1, 2006. Pneumonia was defined as a new or progressive infiltrate on a chest X-ray plus at least two of the following criteria: cough, sputum production, temperature >38°C or <35°C, ausculatory findings consistent with pneumonia, leucocytosis or leucopenia (>10 g/l, <4 g/l or >10% rods in leucocyte differentiation), C-reactive protein >3 times the upper reference value for normal. Patients who were immune compromised (systemic steroid use at admission (prednisone equivalent >20 mg/daily for more than 3 days), haematological malignancies and other immunosuppressive therapy) were excluded. The study was approved by the local Medical Ethics Committee, and informed consent was obtained from each patient. Microbial aetiology workup Mycoplasma pneumoniae Legionella pneumophila Chlamydophyla psittaci 8 Streptococcus pneumoniae L.pneumophila 9 10 Coxiella burnetii M. pneumoniae C. psittaci 11 Exposure to antimicrobial therapy 12 13 Co-morbidity assessment 14 Statistical analysis  SPSS p Results 1 7 14 2 Table 1 Demographics, co-morbidities and pneumonia severity index of 201 patients with community-acquired pneumonia (CAP) Characteristic n Age (Years)   <60 74 (37)   60–69 39 (19)   70–79 50 (25)   >80 38 (19) Gender   Male 124 (62)   Female 77 (38) Co-morbidities   Pulmonary diseases 71 (35)   Heart failure 18 (9)   Diabetes 35 (17)   History of stroke 17 (9)   End-stage renal disease 10 (5)   Nursing home resident 3 (1) Co-medication   Oral corticosteroids 58 (29)   Gastric acid suppressing drugs 61 (30) a   I 30 (15)   II 34 (17)   III 53 (26)   IV 56 (28)   V 28 (14) a 14 Table 2 Outpatient antibiotics utilization profile prior to hospitalisation for CAP Type of antimicrobial drug a b Clavulanic acid 18 (38) Yes Amoxycillin 12 (26) Yes Doxycycline 7 (15) Yes Clarithromycin 5 (11) Yes Co-trimoxazole 4 (8) No Ciprofloxacin 2 (4) No Norfloxacin 1 (2) No Azithromycin 1 (2) Yes a n b 12 13 12 13 3 Table 3 Results of of different tests used to determine the aetiology of CAP   Sputum culture Sputum PCR Antigen testing Blood culture Serology Viral culture Number of samples 148 78 183 182 130 88 Number of positive samples 78 14 36 19 38 14 Percentage of positive samples 53 18 20 10 29 16 Streptococcus pneumoniae 33 – 30 17 – – Gram-negative strain   Heamophilus influenzae 19 – – 0 – –   Other 10 – – 1 – – Atypical   Mycoplasma pneumoniae – 7 – – 8 –   Legionella spp. 1 5 6 – 7 –   Other – 2 – – 1 – Viral – – – – 22 14 Other   S. aureus 6 – – 1 – –   Gram-positive other 2 – – 0 – – S. pneumoniae 4 p p Table 4 Odds ratios (OR) for aetiology and prior outpatient beta-lactam treatment in patients admitted to hospital for CAP Aetiology n OR (95% CI) Yes (%) No (%) Total no. of samples 29 (100) 172 (100)  Univariate   Pneumococcal 4 (14) 56 (33) 0.33 (0.10–0.99)   Atypical 8 (28) 13 (8) 4.66 (1.72–12.56)   Viral 2 (7) 14 (8) 0.84 (0.18–3.89)   Gram-negative strains 2 (7) 21 (12) 0.53 (0.12–2.40)   Other 1 (3) 7 (4) 0.84 (0.10–7.11)   Unidentified 12 (41) 61 (36) 1.28 (0.58–2.87) Multivariate   Pneumococcal – – a   Atypical – – b OR, Odds ratio; CI, confidence Interval a b S. pneumoniae H. influenzae Discussion S. pneumoniae 15 17 S. pneumoniae H. influenzae Legionella spp. C. pneumoniae 13 S. pneumoniae 3 12 13 Legionella spp C. pneumoniae M. pneumoniae 13 18 S. pneumoniae S. pneumoniae 19 20 22 23 S. pneumoniae H. influenzae 6 6 7 In conclusion, among patients admitted for pneumonia, whether or not a patient has received prior antimicrobial therapy as an outpatient provides relevant information in the diagnostic workup, in particular in terms of identifying the causative pathogen and planning the initial treatment at the time of hospital admission. This finding supports a further strengthening of the continuity of care at the interface between the extramural and hospitalised settings.